Chain saw with oil pumping and signaling arrangement

ABSTRACT

Disclosed herein is an oil pumping system or arrangement including a piston which is arranged for rotating and reciprocating movement in a pumping chamber to effect pumping operation, together with means communicating with the pumping chamber for signaling the absence of oil in the system. The piston and the pumping chamber include means for effecting supply and discharge of oil in response to rotary and reciprocating movement of the piston. Such means includes two axially adjacent flats on the piston and location of the inlet and outlet ports in the pumping chamber in axially spaced relation so that both of the inlet and outlet valves are closed during a portion of the piston travel on the compression stroke, whereby to generate a pumping pressure which is utilized in the signaling system. Also disclosed herein is means for reciprocating the pumping piston in response to rotation thereof and for varying the length of piston pumping reciprocation independently of the speed of piston rotation.

United States Patent [1 1 Densow [54] CHAIN SAW WITH OIL PUMPING ANDSIGNALING ARRANGEMENT [75] inventor: Ulrich 0. Densow, Peterborough,

. Ontario, Canada [73] Assignee: Outboard Marine Waukegan, 111.

[22] Filed: Sept. 4, 1970 [211 Appl. No.: 69,686

Corporation,

[52] US. Cl ..l84/6.4, 143/32 A, 184/15 R, 184/33, 417/63 [51] Int. Cl...Fl6n 13/02, Fl6n 29/04 [58] Field of Search ..184/6.4, 1 C, 32, 33, 15R, 184/7 D, 6.28; 340/270; 143/32 A; 417/63,

[ 1 Feb. 20, 1973 Primary Examiner-Manuel A. Antonakas Attorney-RobertK. Gerling, Robert E. Clemency, John W. Michael, Gerrit D. Foster,Bayard H. Michael, Paul R. Puerner, Joseph A. Gemignani, Andrew O.Riteris and Spencer B. Michael [57] ABSTRACT Disclosed herein is an oilpumping system or arrangement including a piston which is arranged forrotating and reciprocating movement in a pumping chamber to effectpumping operation, together with means communicating with the pumpingchamber for signaling the absence of oil in the system. The piston andthe pumping chamber include means for effecting supply and discharge ofoil in response to rotary and reciprocating movement of the piston. Suchmeans includes two axially adjacent flats on the piston and location ofthe inlet and outlet ports in the pumping chamber in axially spacedrelation so that both of the inlet and outlet valves are closed during aportion of the piston travel on the compression stroke, whereby togenerate a pumping pressure which is utilized in the signaling system.Also disclosed herein is means for reciprocating the pumping piston inresponse to rotation thereof and for varying the length of pistonpumping reciprocation independently of the speed of piston rotation.

12 Claims, 23 Drawing Figures PATENTED FEB 2 01973 SHEET 10$ 4 CHAIN SAWWITII OIL PUMPING AND SIGNALING ARRANGEMENT BACKGROUND OF THE INVENTIONFor some time chain saws have been provided with oil pumpingarrangements for supplying oil from a reservoir to a cutting chain. Somechain saws having included automatic pumping arrangements but sucharrangements lacked any capability for warning the operator of anabsence of oil in the pumping system. Thus, it was possible for theoperator to continue use of the saw without realizing the absence oflubricating oil and therefor run the risk of damaging the saw chain andcutter. In the prior automatic pumping systems, inlet and outlet portswere located in opposing relation to each other and were transversed bya flat on the piston to effect pumping action. However, all of the priorart devices have been without any arrangement for automatically pumpingoil to the saw chain and for informing the operator of an absence of oilin the pumping system. 7

SUMMARY OF THE INVENTION The invention provides a pumping arrangement orsystem including automatic signaling means for informing the operator ofan absence of oil in the pumping system. In one disclosed construction.the absence of oil in the pumping system is indicated by theillumination of a light. Other arrangements are also within the over-allcontext of the invention.

The invention also provides an arrangement where the signaling means isbiased toafford indication of an absence of oil in the lubricatingsystem,.together with an arrangement for overpowering the biasing meansto avoid signaling the operator in response to the develop ment ofpumping pressure in the pumping system:

The invention also provides a pumping arrangement which includes arotary and reciprocating piston for effecting pumping operation andwhich is designed so that a period of reciprocation occurs during thecom pression stroke and prior to the opening of the outlet port togenerate pumping pressure and to effect dis placement of a plungeroperating thesignaling means.

I In this regard, in accordance with the invention, the

piston includes two axially adjacent flats which have a common edge butdiffering angular extent, and which are respectively associated with theinlet and outlet ports.

Also in accordance with the invention, the pumping arrangement isprovided with means for reciprocating the piston in response to pistonrotation and for varying the extent of piston reciprocationindependently of the rate of piston rotation.

One of the principal objects of the invention is the provision of asuperior oil pumping arrangement or system for a saw chain, whicharrangement includes means for signaling the operator when there is anabsence of oil in the pumping system Another of the principal objects ofthe invention is the provision of a signaling device for an oil pumpingarrangement in a chain saw, which device includes a light, together withnormally closed switch means .con-

necting the light to a source of power, such as a magthe light, until anabsence of oil develops in the pumping system.

Another of the principal objects of the invention is the provision of apumping system or arrangement in which a reciprocating and rotary pistonis operative to move inwardly of a pumping chamber between closure of aninlet port and opening of an outlet port, thereby to generate pressurewhich can be utilized in a signaling means adapted to warn the operatorof an absence of oil in the oil pumping system.

Another of the principal objects of the invention is the provision of anoil pumping arrangement including means for reciprocating a piston inresponse to piston rotation and for varying the length of pistonreciprocation independently of the speed of piston rotation.

A still further object of the invention is the provision of a simple andeconomical pumping system or arrangement which will provide a long anduseful life, which is especially adapted to use in a chain saw, andwhich will effectively signal the operator to warn of an absence of oilin the oil pumping system.

Other objects and advantages of the invention will becomeknown byreference to the following description and accompanying drawings.

DRAWINGS FIG. 5 is aside view of the structure shown in FIG. 4, I

partially broken away and in section, along line 5-5 of FIG. 4.

FIG. 6 is a wiring diagram of the electrical circuit embodied in the sawchain shown in FIG. 1.

FIG. 7'is an enlarged fragmentary 'view, partially in section, of aportion of the device shown in FIG. 3.

FIGS. 8, 9, I0, 11, 12, I3, and 14 are schematic views showing thesequential operation of the pumping structure shown in FIG. 3, with FIG.8 being taken generally along line 8-8 of FIG. 8A and with the otherviews having a similar orientation. 2

FIGS. 8A, 9A, 10A, 11A, 12A, 13A, and 14A are schematic end viewsillustrating the position of the pumping components in FIGS. 8 through14 respectively.

FIG. 15 is a schematic view of another pumping arrangement embodyingvarious of the features of the invention.

FIG. 16 is a sectional view taken generally along line 16-16 ofFIG. l5.

DETAILED DESCRIPTION Shown in the drawings is a chain saw 11 whichincludes an oil pumping system or arrangement 13 (See FIG. 2) inaccordance with the invention. The chain saw 11 includes a frame 17supporting an engine 19 (shown fragmentarily in FIG. 2) having an outputshaft 21 and an ignition system (not shown) powered by a 1.. wgwawgg hamagneto 22 (See FIG. 6). The frame 17 also supports a cutter bar '23around which is trained a saw chain 27 drivingly engaged by a sprocket(not shown) driven by the engine output shaft 21. In addition, the frame17 also supports a lubricating oil reservoir 29 (See FIG. 2)communicating through a duct 31 with the oil pumping arrangement 13which, in turn, communicates through a duct 33 having an outlet 37-adjacent to the cutter bar 23 to effect supply of lubricating oil to thesaw chain 27.

In general accordance with the invention, the oil pumping arrangement 13generally includes an oil pumping means or system and signal meansoperable to indicate a lack of oil in the pumping means or system.

The oil pumping system comprises a housing 39 (See especially FIG. 3)supported by the frame 17 and including a pumping chamber 41, a pumpingpiston 43 extending into the pumping chamber 41, means 47 for rotatingthe piston 43 in the pumping chamber 41, and means 49 for reciprocatingthe piston 43 in the pump ing chamber 41, whereby to effect pumpingoperation incident to reciprocating and rotating action. The signalmeans comprises means communicating with the pumping chamber andincluding an indicator light 51 V, (See FIG. 6) for signaling theabsence of oil pressure ing means includes normally closed switch means53.

( See FIGS. 2 and 6) connected to the indicator light 51 and to a sourceof electrical power and means 57 operably'connected to the switch means53 for opening the switch means 53 in response to oil pressure generatedin the pumping chamber 41, whereby the indicator light 51 is illuminatedwhen there is an absence of oil pressure in the pumping chamber 41 eventhough the engine 19 is operating.

The pumping operation provided by the piston 43 and the pumping chamber41 is afforded by cooperating means on the pumping chamber and on thepiston for effecting supply and discharge of oil through the ducts 31and 33 in response to rotary and reciprocating movement of the piston43. In the disclosed construction, the means 49 for reciprocating thepiston' 43 in-.

cludes means for effecting piston reciprocation in response to pistonrotation and for varying the distance through which the pistonreciprocatesa More particularly, the pumping system includes (See FIG. 3and FIGS. 8 through 14) in the frame or housing 17 a bore 59 which, inpart, forms the pumping chamber 41. At one end, the bore 59 is closed bymeans including a bushing 61 having an axial bore 63 and by a plunger 67which is reciprocable in the bore 63 and forms a part of the signalingmeans. The pumping chamber 41 is further defined by the rotatable andaxially reciprocable piston 43 extending into the bore 59.

Opening into the bore 59 and communicating with the pumping chamber 41in diametrically opposed and axially spaced relationship are an inletport 69 communicating with the duct 31 and an outlet port 71communicating with the duct 33. The inlet port 69 is located adjacent tothe end of the pumping chamber 41 formed by the bushing 61 and inposition to be opened and closed in response to piston rotation. Theoutlet port 71 is also located so as to be opened and closed by thepiston in response to piston rotation.

Cooperating 'means are provided on the piston 43 and on the pumpingchamber 41 tov effect periodic opening and closing of the inlet andoutlet ports 69 and 71, respectively, and thereby toeffect pumpingaction from the reservoir 29, through the pumping chamber 41 and to theoutlet 37 in response to piston reciprocation and rotation. Whilevarious arrangements can be employed, in the disclosed construction, thepiston 43 includes (See FIGS. 8 and 8A) a maincylindrical portion 73,together with an inner end portion 77 which extends from the maincylindrical portion 73 and an outer end portion 79 which extends fromthe inner end portion 77. The inner end portion 77 is cylindrically Y 81when the piston 43 is at its most retracted position. Furthermore, it isto be understood that the maximum axial travel of the piston 43 is aboutthe same as, and is not greater than, the axial length of theflat81.-Thus, during operation, the piston reciprocation is so limitedthat the inner end portion 77 is always opposed to the outlet port 71and so that the outlet port 71 is opened during travel of the flat 81therepast and is closed at all other'tirnes by the cylindrical surfaceportion 83 of the inner end portion.

The outer end portion 79 is slightly greater. than semiecylindrical inshape having a flat 87 which subtends an angle of just less than degreesas shown in FIG. 8A. The flat 87 includes an edge 89 which is axially inregister with the-trailing edge of 'the flat 81 as determined by thepiston rotation whichis shown to be clockwise-in FIG. 8, The outer endportion 79 has an axial length approximately equal to the axial lengthof the inner end portion 77 and is always opposed to the inlet port69,notwithstanding piston reciprocation. Accordingly, the inlet port 69will be open whenever the flat 87 travelspast the port 69 (for almost180 degrees .of rotationland is closed during rotary movement of thecylindrical portion surface 91 past the inlet port 69 (during about alittle more than 180 degrees of travel).

As already indicated, respective means 47 and 49 are provided forrotating the piston 43 and for reciprocating the piston 43 within thebore 59 within an axial range having a maximum axialextent of about theaxial length of the inner and end portions 77'and .79 respectively ofthe piston 43. More specificall'y,-while various arrangements can beemployed, in the disclosed construction, the means 47 for rotating thepiston 43 comprising a worm 93 on the engine output shaft 21 or on someother shaft driven by the engine 19 and a pinion 97 on a part 99 of thepiston 43 remote from the pumping' chamber 41 and in mesh with the worm93 for effecting piston rotation at a reduced speed as compared toengine speed. The connection of the pinion 97 with the piston part 99provides common rotary movement while affording axial movement of thepiston 43 relative to the pinion 97 to accommodate piston reciprocation.

While various arrangements .can be employed to reciprocate the piston 43in response to piston rotation on a stud 113 on the frame 17. The ringmember includes a bore 117 receiving another part 119 of the piston 43remote from the chamber 41. Extending radially from the piston part 119is a follower pin 121 which is received (See FIG. 4) in an interiorannular groove 123 located in the bore 117 of the ring member 111 in asingle transverse plane. Accordingly, when the ringmember 111 is locatedon the pivot or stud 113 with the annular groove 123 perpendicular tothe axis of piston rotation, such piston rotation will be inefiective tocause piston reciprocation. However, when the ring member 111 is pivotedfrom such perpendicular relation, the groove 123 then has an axialextent relative to the piston 43 and circular movement of the followerpin 121 in the groove 123 will cause piston reciprocation proportionateto the angular displacement of the ring member 111 from the position inwhich the groove 123 is perpendicular to the piston axis. Preferably,the ring member 111 includes a pointer 127 which is movable relative toa scale 129 located on the frame 17 and having suitable indicia so as toinform the operator of the extent of the reciprocating movement or thequantity or amount of oil being pumped in response to piston rotation.

Means in the form of a setscrew 131 (See FIG. 5) can be used toreleasably retain the ring member 111 at any desired angular settingrelative to the setting shown in full lines in FIG. 4.

While various arrangements can be employed, in the disclosedconstruction, the before mentioned signal generating means includes thebefore mentioned plunger 67 which serves the dual purpose of assistingin closing one end of the pumping chamber 41 and acting as a switchoperator or actuator. More particularly, the bore 59 includes, at theplunger end thereof, two related counterbores 133 and 137 (See FIG. 3)with the inner counterbore 133 having a greater diameter than the bore59. In addition, the plunger 67 includes a collar or sleeve 139 which isreciprocally guided in the inner counterbore 133 and which serves as aseat for means in the form of a spring 141 for biasing the plunger 67inwardly toward the pumping chamber 41. At its outer end, the spring 141is seated against a plug 143 which is threadedly received in the outercounterbore 137 and which includes a central aperture 147 through whichthe plunger 67 extends and is guided for reciprocation.

The outer end 149 of the plunger 67 contacts a switch blade or contactmember 151 forming a part of the normally closed switch means 53 whichis operative to supply current to the indicating light 51 from a sourceof current. While various current sources can be employed, in thedisclosed construction, the magneto 22 generates current to energize thelight whenever the engine 19 is operating and the switch means 53 isclosed, thereby to signal the operator that there is a lack of oil inthe pumping system.

- Means are provided between the pumping chamber 41 and the plunger 67for immediately subjecting the sure condition occurring over a durationincluding plunger 67 to pumping pressure during the inward movement ofthe piston 43 relative to the pumping chamber 41 by affording relativefree flow from the pumping chamber 41 toward theplunger 67 and forrestricting oil flow from in front of the plunger 67.back to the pumpingchamber 41 whenthe piston 43 is retracting to afford supply of oil intothe pumping chamber 41 from the reservoir 29 through the inlet port 69.Thus, the plunger 67 will not move away from an extended positionretaining the switch means 53 opened unless low pressure exists in thepumping chamber 41 for a time interval far greater than the timeinterval of one half of the piston reciprocation cycle. As a result, theplunger 67 is insensitive to the withdrawal stroke of the piston 43relative to the pumping chamber 41 but does sense a continued lowpresseveral cycles of piston reciprocation. Under such continuedconditions of low pressure, the spring 141 will urge the plunger 67inwardly, thereby permitting the switch means 53 to close andilluminating the light 51 indicating absence of oil flow.

While various arrangements could be employed, in the disclosedconstruction, the means for regulating or controlling oil flow betweenthe pumping chamber 41 and the area immediately in front of the plunger67 comprises a rigid disc 161 (See particularly FIG. 7) which is locatedadjacent to the end of the bushing 61' adjacent to the pumping chamber41, and which has therein a relatively restricted central aperture 163.Retained between the disc 161 and the adjacent end of the bushing 61 isa flexible member 165 which is suitably apertured as, for instance, by acentered slit 169, or by centered cross slits, to permit relatively freedeflection into the bushing bore for relatively unrestricted oil flowthrough the aperture 163 in the disc 161 in response to higher pressurein the pumping chamber 41 than in the-area ahead of the plunger 67. Suchcapacity for unrestricted flow will cause the plunger 67 to be extendedto open the normally closed switch means 53. However, when the pressurein the pumping chamber 41 is temporarily less than in the area ahead ofthe plunger 67 as, for instance, when the piston 43 is being withdrawnfrom the pumping chamber 41 during the intake stroke, the restrictedaperture 163 in the disc 161 serves to prevent such closing of theswitch means 53. However, should the condition of low pressure continueover a timer interval of several reciprocation cycles, sufficient flowthrough the slit or slits .169 in the flexible member 165 and 7 throughthe central aperture 163 in the disc 161 will occur to afford inwarddisplacement of the plunger 67 by the spring 141 and consequent closingof the switch means 53 to illuminate the light 51 and to indicate to Thepumping and signaling operation is as follows: When the piston 43 isfully retracted or withdrawn, both the inlet and outlet ports 69 and 71,respectively, are closed and the'outlet port 71 is located for theparticular reciprocation range (See FIGS. 8 and 8A) at a maximumdistance from the end of the flat 81 adjacent to the cylinder portion73. In addition, the spring 141 biases the plunger 67 to a fullyinserted position within the bushing 61. Upon piston rotation, thepiston begins to advance into the pumping chamber 41. During the first45 to 60 degrees of movement (See FIGS. 9 and 9A), the piston movesapproximately one-fourth of its full stroke while both the inlet andoutlet ports 69 and 71 are closed. Because of the incompressability ofthe oil, the volume of oil defined by this one-fourth stroke is forcedinto the bushing 61 and extends the plunger 67 to open the switch means53 preventing illumination of the light 51. When the piston has rotatedat least about 45 degrees, the flat 81 begins to travel past the outletport 71 (See FIGS. 10 and 10A) and as. the piston 43 continues movementinwardly of the pumping chamber 43, the oil in the pumping chamber 43'travels past the outer and inner flats 87 and 81, respectively, and outthe outlet port 71. When the piston has rotated about 180 degrees fromits starting position (See FIGS. 11 and 11A), the piston 43 is fullyinserted within the pumping chamber 41 and the outlet port 71 is closed.During the first 180 degrees of rotation, the inlet port 69 has remainedclosed due to blockage by the surface 91. However, as the piston 43continues its rotation and begins its withdrawal, the inlet port 69 isopened (See FIGS. 12 and 12A) to permit flow into the area in front ofthe flat 87 and into the pumping chamber 41 in general. I

The inlet port 69 remains open until just less than 360 degrees ofrotation until the piston 43 is fully withdrawn and is closed upon fullwithdrawal of the piston 43. As already explained, flow restrictionprovided by the disc 161 and flexible member 165 permit retention ofpressure oil in the bushing 61 to retain the switch means 53 in openposition until pressurized oil is again generated in response to pistonmovement inwardly of the pumping cylinder. Accordingly, it is seen thatthe disclosed arrangement provides periodic pumping from the inlet tothe outlet and also serves to retain the switch means 53 in the off oropen position so long as there is ample oil in the system. However,should air enter into the pumping chamber 41, inward movement of thepiston 43 is insufficient to cause enough pressure to effect andmaintain withdrawal of the plunger 67 and consequent opening of theswitch.

means 53. Under these circumstances, the switch means 53 will be closedand the light 51 will be illuminated to notify the operator of a lack ofoil in the pumping system.

Another pumping arrangement 175 embodying various of the features of theinvention is shown in FIG. 15. The pumping arrangement 175 includes ahousing 177 defining a pumping chamber 179 having a closed end.

Received in the pumping chamber 179 is a pumping piston 181 whichincludes a single flat 183 sub-tending an angle of about 150 degrees andwhich is rotatably and reciprocably driven in the pumping chamber 179relative to diametrically opposed inlet and outlet ports 185 and 187,respectively.

The outlet port 187 communicates through a duct 189 with one end of acylinder 191 having therein a piston 193 operably connected to asignaling flag 195 which is mounted for pivotal movement on a stud 197extending from .the housing 177 and which includes a flag portion 199and an arm 201 extending from the stud 197 in the opposite directionfrom the flag portion 199.

Means in the form of a leaf spring 203 engaged between the housing 177and the flag portion 199 of the flag 195 is provided for biasing theflag portion 199 out of a pocket 205 in the housing 177 and in theclockwise direction to a position which can be readily seen by theoperatorand so as to engage the arm 201 against a protuberance or lug207 on the other end of the piston 193, thereby urging the piston 193inwardly of the cylinder 191 and toa position closing a delivery port211 and connected duct 213 extending radially from the cylinder 191.

In operation of the arrangement or system shown in FIGS. 15 and 16,rotative and reciprocating movement of the piston 181 causes a pumpingaction in the pumping chamber 179 and the consequent'oil flow throughthe outlet port 187 and into the cylinder 191.Such flow causes thepiston 193 to be displaced to the right as shown in FIG. 15, against theaction of the spring 203 to communicate the exhaust or outlet port 187of the pumping chamber 179 with the delivery duct 213 and, at the sametime, to displace the flag portion 199 into the pocket205 and generallyout of the view of the operator. Failure of retraction of the flagportion 199 into the pocket 205 indicates to the operator the absence ofoil in the pumping system.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is: g

1. An oil pumping arrangement comprising a housing including a pumpingchamber having opposite ends, a pumping piston extending into saidpumping chamber from one of the ends thereof, means for rotating saidpiston'in said pumping chamber, means for reciprocating said piston insaid pumping chamber, in response to piston rotation, whereby to effectpumping'operation incident to said reciprocating and rotary action, andsignal means communicating with said pumping chamber and responsive tothe failure of oil pressure therein and including a plunger extendinginto said pumping chamber from the other of said ends.

2. An oil pumping arrangement in accordance with claim 1 and furtherincluding. means biasing said plunger inwardly of said pumping chamber.

3. An oil pumping arrangement comprising a housing including a pumpingchamber having a main portion with a cylindrical shape, an inlet-borecommunicating with said pumping chamber, and an outlet borecommunicating with said pumping chamber and being spaced axially of saidpumping chamber and angularly from said inlet bore, a pumping pistonextending into said pumping chamber and having a main portion with adiameter closely fitting said cylindrical shape of said pumping chamber,an inner end portion extending fromsaid main portion and having a lessercross sectional area than said main portion, and an outer end portionextending from said inner end portion and having a lesser crosssectional area than said inner end portion, whereby to effect pumpingoperation incident to said reciprocating and rotary action, and meanscommunicating with said pumping chamber for signaling the failure ofpressure within the oil in said pumping chamber.

4. An oil pumping arrangement comprising a housing including a pumpingchamber, a pumping piston extending into said pumping chamber andincluding a part located externally of said pumping chamber, means forrotating said piston, a ring member having an internal-bore receivingsaid piston part and including an internal surface with an annulargroove therein, a follower extending radially from said piston part andreceived in said groove, and means mounting said 'ring member foradjustable angular positioning relative to said piston part about anaxis transverse to the rotary axis of said piston, whereby toreciprocate said piston in response to rotation thereof and whereby tovary the stroke of reciprocation in response to angular adjustment inthe position of said ring member.

5. An oil pumping arrangement comprising a housing including a pumpingchamber, a pumping piston extending into said pumping chamber, means forrotating said piston in said pumping chamber, means for reciprocatingsaid piston in said pumping chamber, whereby to effect pumping operationincident to said reciprocating and rotary action, a source of electricalpower, an indicator light, normally closed switch means connecting saidlight to said power source, and means operably connected to said switchmeans for opening said switch means in response to oil pressuregenerated in said pumping chamber, whereby said indicating light is notilluminated when oil pressure is generated in said pumping chamber.

6. An oil pumping arrangement in accordance with claim wherein saidswitch means includes a control member movable relative to a normallyclosed position, and wherein said means for opening said switch meansincludes an oil receiver, a plunger movable in said oil receiver andincluding a part engageable with said contact member to open said switchmeans in response to movement of said plunger in the direction outwardlyof said oil receiver, and an oil flow connection between said oilreceiver and said pumping chamber, said connection includingmeans'affording oil flow from said pumping chamber to said receiver andaffording oil flow from said oil receiver to said pumping chamber whichis restricted as compared to oil flow from said pumping chamber to saidoil receiver.

7. An oil pumping arrangement in accordance with claim 6 wherein saidmeans affording oil flow between said pumping chamber and said oilreceiver includes wall means in said connection defining an aperture anda flexible member adjacent to said wall means and on the side thereofadjacent to said oil receiver and including means therein for affordinga flow opening which is more restrictive by reason of the proximity ofsaid-wall means in response to oil flow from said oil receiver to saidpumping chamber as compared to oil flow from said pumping chamber tosaid oil receiver.

8. An oil pumping arrangement in accordance with claim 6 including meansbiasing said plunger into said oil receiver.

9. A chain saw including a frame, an engine supported on said frame andincluding an output shaft, a

cutter bar extending from said frame, a saw chain trained around saidcutter bar and driven by said engine, an oil supply duct having adischarge adjacent to said cutter bar, an oil reservoir supported bysaid frame and an oil pumping arrangement supported by said frame andincluding a pumping chamber operably communicating with said oilreservoir and said oil supply duct and having opposite ends, a pumpingpiston extending into said pumping chamber from one of the ends thereof,means for rotating said piston in said pumping chamber, means forreciprocating said piston in said pumping chamber in response to pistonrotation including a gear connection between said output shaft and saidpiston, whereby to effect pumping operation incident to saidreciprocating and rotary action, and

signal means communicating with said pumping chamber and responsive tothe failure of oil pressure therein and including a plunger extendinginto said pumping chamber from the other of said ends.

10. An oil pumping arrangement including a pump housing having aninternal bore, an inlet bore communicating with said internal bore, andan outlet bore communicating with said internal bore and being axiallyand diametrically spaced from said inlet bore, a pumping pistonextending into said internal bore from the end adjacent to said outletbore for axial reciprocation and for rotation and having a main portion,an inner end portion extending from said main portion and having alesser cross sectional area than said main portion, and an outer endportion extending from said inner end portion and having a lesser crosssectional area than said inner end portion, means for rotating andreciprocating said pumping piston relative to said housing, a plungerextending into said internal bore from the end adjacent to said inletbore for axial reciprocation relative to said internal bore and subjectto the pressure condition in said internal bore between said pumpingpiston and said plunger and having a part extending from said housing, asource of electrical power, an indicator light, a normally closed switchconnected between said power source and said light and including acontact member movable to open said switch in response to movement ofsaid plunger outwardly of said housing, and means biasing said plungerinwardly of said internal bore.

11. An oil pumping arrangement including a pump housing having aninternal bore with an inlet, an outlet and spaced ends, a pumping pistonextending into said internal bore from one of said ends for axialreciprocation and rotation, means for rotating and reciprocating saidpumping piston relative to said housing, a plunger extending into saidinternal bore from the other of said ends for axial reciprocationrelative to said internal bore and subject to the pressure condition insaid internal bore between said pumping piston and said plunger andhaving a part extending from said housing, and signal means operated bymovement of said plunger relative to said pump housing.

12. An oil pumping arrangement in accordance with claim 11 and furtherincluding means biasing said plunger inwardly of said internal bore andwherein said signal means includes a source of electrical power, anindicator lightand a switch connected between said power source and saidlight and including a contact member movable to actuate said switch inresponse to movement of said plunger outwardly of said housing.

1. An oil pumping arrangement comprising a housing including a pumpingchamber having opposite ends, a pumping piston extending into saidpumping chamber from one of the ends thereof, means for rotating saidpiston in said pumping chamber, means for reciprocating said piston insaid pumping chamber, in response to piston rotation, whereby to effectpumping operation incident to said reciprocating and rotary action, andsignal means communicating with said pumping chamber and responsive tothe failure of oil pressure therein and including a plunger extendinginto said pumping chamber from the other of said ends.
 1. An oil pumpingarrangement comprising a housing including a pumping chamber havingopposite ends, a pumping piston extending into said pumping chamber fromone of the ends thereof, means for rotating said piston in said pumpingchamber, means for reciprocating said piston in said pumping chamber, inresponse to piston rotation, whereby to effect pumping operationincident to said reciprocating and rotary action, and signal meanscommunicating with said pumping chamber and responsive to the failure ofoil pressure therein and including a plunger extending into said pumpingchamber from the other of said ends.
 2. An oil pumping arrangement inaccordance with claim 1 and further including means biasing said plungerinwardly of said pumping chamber.
 3. An oil pumping arrangementcomprising a housing including a pumping chamber having a main portionwith a cylindrical shape, an inlet bore communicating with said pumpingchamber, and an outlet bore communicating with said pumping chamber andbeing spaced axially of said pumping chamber and angularly from saidinlet bore, a pumping piston extending into said pumping chamber andhaving a main portion with a diameter closely fitting said cylindricalshape of said pumping chamber, an inner end portion extending fRom saidmain portion and having a lesser cross sectional area than said mainportion, and an outer end portion extending from said inner end portionand having a lesser cross sectional area than said inner end portion,whereby to effect pumping operation incident to said reciprocating androtary action, and means communicating with said pumping chamber forsignaling the failure of pressure within the oil in said pumpingchamber.
 4. An oil pumping arrangement comprising a housing including apumping chamber, a pumping piston extending into said pumping chamberand including a part located externally of said pumping chamber, meansfor rotating said piston, a ring member having an internal borereceiving said piston part and including an internal surface with anannular groove therein, a follower extending radially from said pistonpart and received in said groove, and means mounting said ring memberfor adjustable angular positioning relative to said piston part about anaxis transverse to the rotary axis of said piston, whereby toreciprocate said piston in response to rotation thereof and whereby tovary the stroke of reciprocation in response to angular adjustment inthe position of said ring member.
 5. An oil pumping arrangementcomprising a housing including a pumping chamber, a pumping pistonextending into said pumping chamber, means for rotating said piston insaid pumping chamber, means for reciprocating said piston in saidpumping chamber, whereby to effect pumping operation incident to saidreciprocating and rotary action, a source of electrical power, anindicator light, normally closed switch means connecting said light tosaid power source, and means operably connected to said switch means foropening said switch means in response to oil pressure generated in saidpumping chamber, whereby said indicating light is not illuminated whenoil pressure is generated in said pumping chamber.
 6. An oil pumpingarrangement in accordance with claim 5 wherein said switch meansincludes a control member movable relative to a normally closedposition, and wherein said means for opening said switch means includesan oil receiver, a plunger movable in said oil receiver and including apart engageable with said contact member to open said switch means inresponse to movement of said plunger in the direction outwardly of saidoil receiver, and an oil flow connection between said oil receiver andsaid pumping chamber, said connection including means affording oil flowfrom said pumping chamber to said receiver and affording oil flow fromsaid oil receiver to said pumping chamber which is restricted ascompared to oil flow from said pumping chamber to said oil receiver. 7.An oil pumping arrangement in accordance with claim 6 wherein said meansaffording oil flow between said pumping chamber and said oil receiverincludes wall means in said connection defining an aperture and aflexible member adjacent to said wall means and on the side thereofadjacent to said oil receiver and including means therein for affordinga flow opening which is more restrictive by reason of the proximity ofsaid wall means in response to oil flow from said oil receiver to saidpumping chamber as compared to oil flow from said pumping chamber tosaid oil receiver.
 8. An oil pumping arrangement in accordance withclaim 6 including means biasing said plunger into said oil receiver. 9.A chain saw including a frame, an engine supported on said frame andincluding an output shaft, a cutter bar extending from said frame, a sawchain trained around said cutter bar and driven by said engine, an oilsupply duct having a discharge adjacent to said cutter bar, an oilreservoir supported by said frame and an oil pumping arrangementsupported by said frame and including a pumping chamber operablycommunicating with said oil reservoir and said oil supply duct andhaving opposite ends, a pumping piston extending into said pumpingchamber from one of the ends thereof, means for rotating said piston inSaid pumping chamber, means for reciprocating said piston in saidpumping chamber in response to piston rotation including a gearconnection between said output shaft and said piston, whereby to effectpumping operation incident to said reciprocating and rotary action, andsignal means communicating with said pumping chamber and responsive tothe failure of oil pressure therein and including a plunger extendinginto said pumping chamber from the other of said ends.
 10. An oilpumping arrangement including a pump housing having an internal bore, aninlet bore communicating with said internal bore, and an outlet borecommunicating with said internal bore and being axially anddiametrically spaced from said inlet bore, a pumping piston extendinginto said internal bore from the end adjacent to said outlet bore foraxial reciprocation and for rotation and having a main portion, an innerend portion extending from said main portion and having a lesser crosssectional area than said main portion, and an outer end portionextending from said inner end portion and having a lesser crosssectional area than said inner end portion, means for rotating andreciprocating said pumping piston relative to said housing, a plungerextending into said internal bore from the end adjacent to said inletbore for axial reciprocation relative to said internal bore and subjectto the pressure condition in said internal bore between said pumpingpiston and said plunger and having a part extending from said housing, asource of electrical power, an indicator light, a normally closed switchconnected between said power source and said light and including acontact member movable to open said switch in response to movement ofsaid plunger outwardly of said housing, and means biasing said plungerinwardly of said internal bore.
 11. An oil pumping arrangement includinga pump housing having an internal bore with an inlet, an outlet andspaced ends, a pumping piston extending into said internal bore from oneof said ends for axial reciprocation and rotation, means for rotatingand reciprocating said pumping piston relative to said housing, aplunger extending into said internal bore from the other of said endsfor axial reciprocation relative to said internal bore and subject tothe pressure condition in said internal bore between said pumping pistonand said plunger and having a part extending from said housing, andsignal means operated by movement of said plunger relative to said pumphousing.